A common question on every gardener’s mind in the fall is whether or not they should prune their hydrangea. It all depends on which type of hydrangea you have. Some types bloom on old wood, meaning they’ve formed their flower buds in the prior season. If you cut back a stem in the fall that contains the flower buds for the next season, you’ve just sacrificed next year’s flowers!
Other species grow on new wood only, which means they form their flower buds on the current season’s growth. These types are quite suitable for colder climates, where there is no chance of the flowers buds being harmed over the winter. Some newer introductions combine both traits which bloom on both old wood and new wood.
Here are the four most common types of hydrangea:
- Panicle hydrangeas, sometimes referred to as Pee Gee Hydrangeas or Hydrangea paniculata, are a variety that blooms on new wood only. This group can be pruned in fall or very early spring, but we highly recommend waiting until the spring to reduce risk of injury.
- Smooth hydrangeas, also known as Annabelle Hydrangeas or Hydrangea arborescens, also bloom on new wood only. Just like the last group, these can be pruned in fall, but we recommend waiting until early spring.
- Oakleaf Hydrangeas, or Hydrangea quercifolia, are a variety that bloom on old wood only. Because of this, it’s important to prune just as the season’s flowers are fading, and no later.
- Mophead Hydrangeas, or Hydrangea macrophylla, are a tricky group. All varieties bloom on old wood, but some, especially newer introductions, bloom on both old and new growth. You should only prune these types of hydrangeas just after the flowers have faded.